Motor-control system



MOTOR CONTROL SYSTEM Filed NOV. 10. 1924 |n\/entor- 2 .Jol'n'w- A. Hepperlen,

y His Attorney.

Patented Dec. 6, 1927.

UNITED, STATES 1,651,889 PATENT OFFICE.

JOHN A. HEPPERLEN, OF EAST ORANGE, NEW JERSEY, ASSIGNOR 'IO GENERAL ELEC- TRIO COMPANY, A CORPORATION OF NEW YORK.

MOTOR-CONTROL SYSTEM.

Application filed November 10, 1924. Serial No. 748,817.

My invention relates to improvements in motor control systems, and in. particular to systems whereby the motor may be remotely controlled by means of separately operable manually operated switches, such as push button switches or the like, located at themotely controlled without the necessity of using the dash pots, ratchet switches, pilot motor operated controllers, dial switches or drum type switches as heretofore employed. Another object of the invention is the provision of a system of the character indicated wherein means is provided whereby the motor may be accelerated from standstill to either of a plurality of definite speeds by simply momentarily depressing the push button switch corresponding to the particular speed desired. Thus, in case it is desired that the motor shall have a definite full running speed, a definite half speed and a defi nite slow speed, the arrangement shall'be such that by merely momentarily depressing the particular push button switch designated for the particular speed desired, the motor will be accelerated from standstill to the full running speed, the half speed or the low speed.

A further object of the invention is the provision of a system of the character indicated wherein means is provided whereby the speed of the motor may be changed from any definite speed to either a higher speed or a lower speed while the motor is running, by merely momentarily depressing the particular push button switch for the particular speed selected.

A still further object of the invention is the provision of a system wherein means is provided for signalling the particular speed selected so that the selected speed can be observed from a distance,

These and other objects of the invention, 00'. as will be either fully pointed out hereinafter or as will be apparentto those skilled in the art from an understanding of the invention, are attained in the system which is illus trated in very simple diagram in the accompanying drawing which shows an embodiment of the invention which I now regard as the preferred form of the invention.

Referring to the drawing, the electric motor to be controlled in accordance with the invention is indicated as of the direct current type having an armature 10 and a shunt field 11. This motor is arranged to be conneoted to the direct current source of supply 12 under the control of the line contactor 13. The variable resistance 14 is included in the motor armature circuit and this resistance is under the control of an electromagnetic switch or contactor 15, the coil of which is arranged to be energized in response to the counter electromotive force of the motor armature 10 when the line contactor'13 has closed. This contactor 15 is arranged to short-circuit the left hand portion of the resistor 14 and at the same time include the series coil of the series contactor 16 in the motor armature circuit so that the entire re-- sistance 14 will be short circuited by the contactor 16 when the current taken by the m0- tor decreases to the predetermined value during the acceleration of a motor. After the motor has accelerated to what may be termed basic s speed corresponding to t e full field speed with all of the armature resistance shortcircuited, further increase in the motor speed is accomplished by controlling the resistance in the circuit of the shunt field of the motor. This resistance is designated as having two sections 17 and 18. The electromagnetic switch or contactor 19 is provided for shortcircuit-ing the resistance section 18 and the contactor 20 is provided for short-circuiting both of the sections 17 and 18 so as to obtain full field of the motor and obtain a definite low speed of the motor which corresponds to the full field relation. The relay 21 is provided for insuring that the resistance sections 17 and 18 will be short-circuited during the starting and acceleration of the motor by' armature resistance control. This relay is shown as having its winding connected across the resistance 14 in the motor armature circuit, so as to be energized in accordance with the voltage drop across this resistance. The relay 22 is provided for establishing and maintaining the coil winding circuit of the line contactor 13.

The various contactors are under the selective control of a plurality of separately operable, manually operated switches, each eed, that is, the

of which is biased to a predetermined position, and each of which corresponds to a definite speed of the motor. These manually operated switches are preferably in the form of spring return push button switches as indicated. The push button switch 23 is provided for obtaining a selective control of certain of the contactors in order to obtain the full speed relation of the motor, that is, the connection of the motor in which the armature resistance let is automatically short-circuited and the motor is gradually accelerated to full running speed with both of the sections 17 and 18 of the field resistance included in the motor field circuit. The push button 24 is provided for establishing what may be termed the half speed of the motor, that is, one in which the armature resistance 14: is automatically short-- circuited and the motor is automatically accelerated to a speed corresponding to a speed obtained in which the section of the field resistance 17 is included in the motor field circuit. The push button switch 25 is provided for obtaining a selective operation of the contactors so as to obtain a speed of the motor corresponding to that which is obtained with all of the resistance 14 shortcircuited and the sections 17 and 18 of the shunt field resistance short-circuited. This push button ma be termed the slow speed ush button an in the arrangement shown in the drawing, this slow speed corresponds to the basic speed. The push button 26 is a stop push button provided for the purpose of disconnectin the motor from the supply circuit at the Wlll of the o erator.

The arrangement is suc that these push buttons are electricall connected with the various contactors and relays of the system in such a manner that control of the motor speed may be had at all times by simply momentarily depressing and then releasing the particular push button which corresponds to the definite speed desired. These electrical connections are such that the motor ma not only be accelerated from rest automatically to any one of the definite speeds corresponding to the respective push buttons, but in case it is desired to either increase or decrease the motor speed while the motor is running, the electrical connections are such that this may be done by merely momentarily depressing the particular push button for the speed desired. Thus in case the motor was accelerated from rest under the control of the push button 24, the half speed push button, in case it is desired to efl'ect an mcrease of the motor speed, the push button 23 will be momentarily depressed and then released and the full speed of the motor will be automatically obtained. In case it were desired to decrease the speed of the motor from the half speed, the slow speed push button 25 will be momentarily deressed and released and the slow speed reation of the motor will be obtained. As

will be pointed out particularly hereinafter,

controllers, dial switches or drum type switches as have heretofore been provided for accomplishing the nicety of control effected through the comparatively simple system of the present invention.

For certain applications it is desirable that there may be a visible indication. of the speed at which the motor is operated, and for this purpose I have provided the signal lamps 27, 28 and 29, corresponding respectively to the full speed of the motor, the half speed of the motor and the slow speed. These signal lamps may be difli'erentlated from each other by being colored difierently or in any other suitable manner to indicate at a distance the desired signal intended. The arrangement is such that one of these signal lamps will be lit, corresponding to the push button which was depressed to obtain the particular speed desired and the arrangement is also such that the signal lamp will remain lighted after the particular push button has been depressed. In other 'words, as long as the motor is operating at the particular speed desired, the signal lamp correspondin to that speed will remain lighted. If the speed of the motor is altered under the control of the push buttons 23, 24 and 25, the signal lamps will also be correspondingly controlled so that only one lamp will be lit at a time and that lamp will correspond to the speed at which the motor is operating.

As thus constructed and arranged, the operation of my invention is as follows: Let it be assumed that the operator desires to have the motor accelerated from rest to the full running speed. \Vith the parts in their respective positions shown in the drawing, if the push button switch 23 is momentarily depressed so as to make engagement with its lower set of contacts, a circuit will be established for the coil of the relay 22, the circuit being from the lower conductor of supply circuit 12, through the contacts of the overload relay 30, the stop push button 26, the lower contacts of the push button switch 23, the auxiliary contacts 31 of contactor 20, auxiliary contacts 32 of contactor 19, through the coil of the relay 22 to the upper conductor of the source of supply 12. The relay 22 will at once respond and es- .tablish a maintaining circuit for its coil through the auxiliary switch 33 associated -cluded in circuit therewith.

with the relay 22 so that releasing the push button 23 will have no effect upon the energization of the relay 22. When the relay 22 closes, it establishes a circuit for the coil of the line contactor 13 so that this line contactor coil is connected directly across the source of supply 12. This circuit may be very readily traced. It will also be observed that the signal, lamp 27 will now receive energy through a circuit including the contacts of the overload relay 30, the stop push button switch 26, the auxiliary switch 33 of relay 22, auxiliary switch 32 of contactor 19, aux- 1l iary switch 31 of contactor 20, through the signal lamp to the upper supply conductor.

The closing of the line contactor 13 will connect the motor armature to the source of supply 12 with the armature resistance 14 in- The shunt field winding 11 of the motor will also be energized from the supply circuit, and by reason of the fact that the coil of relay 21 is connected across the armature resistance 14, this relay will be energized to close and short--circuit the sections 17 and 18 of the shunt field resistance. The relay 34, which has its cOil in the motor armature circuit, will also be energized to close its contacts by reason of the fact that the motor armature current at starting'is relatively high. The contacts of this relay establish another shunt about the field resistances 17 and 18, although this relay performs no particular function during the acceleration of the motor by varying the armature resistance 14. This relay 34 is particularly useful for obtaining a smooth acceleration of the motor when the speed variation is obtained by varying the shunt field excitation.

' When the line contactor 13 closes, it es-' tablishes a circuit for the coil of the accelerating contactor 15 so that the coil of this contactor is energized responsively to the generated potential of the armature 10 through the auxiliary contacts 35. When the motor accelerates to a definite value corresponding to the value for which the contac- 'tor 15 is set to operate, this contactor 15 will be energized to close and thus shunt the left-hand portion of the resistance 14, at the same time including the series coil 36 of the series contactor 16 inthe motor armature circuit. This contactor 16 is of the well known type which magnetically holds open when the current in its series coil is above a predetermined value and magnetically closes when the current in the series coil drops to a predetermined value. When the current taken by the motor armature drops to the predetermined value, the contactor 16 will be magnetically closed and shunt the armature resistance 14, at the same time shunting the series coil 36 of the contacton. The contactor 16 is maintained closed by means of the shunt coil 37 which is energized through the auxiliary switch 38 associated with the contactor 15. When the resistance 14 is thus shunted, the coil of relay 21 is also shunted and this relay will open. If the motor armature current has not dropped to the predetermined value for which the relay 34 is set, the sections of the resistances 17 and 18 in the motor field circuit will remain shunted through the contacts of the relay 34. However, as soon as the motor armature current drops to the predetermined value, the relay 34 will open its contacts and insert the resistance sections 17 and 18 in the shunt field circuit. This will effect an acceleration of the motor and in all probability the armature current will rise to such a value that the relay 34 will again close its contacts. The relay 34 will thus alternately open and close, depending upon the motor armature current until the motor has accelerated in a smooth and gradual manner to the full speed under field control, at which time the relay 34 will remain open.

If it had been desired to accelerate the motor from rest to the half speed relation, the push button 24 would have been momentarily closed instead of thepush button 23. The operation will be the same as before except that in this case the field contactor 19 will be energized so as to short-circuit the resistance section 18 in the shunt field circuit.

the upper contacts of the push button 25,

the upper contacts 40 of the field contactor 19, through the right-hand lower contact of the push button 24, through the signal lamp to the upper supply conductor of the source 12. The motor will accelerate as before with the full field relation. established by the relay 21 and the relay 34, the contactors 15 and 16 automatically closing to short-circuit the armature resistance 14 in a manner previously explained. When the armature resistance'14 has been short-circuitcd' and the relay 21 de-energized and opened, the resistancesection 17 will be included in the shunt field circuit and the motor will be automatically accelerated to the predetermined speed under the control of the fiutten ing relay 34.

In case it is desired to initially accelerate the motor from rest to the slow speed rela tion, the push button 25 will be momentarily depressed, thereby energizing the field contactor 20 to close and short-circuit the field resistance sections 17 and 18. The relay 22 in this case will be energized to close through auxiliary contacts 11 of the contactor 20, and the signal lamp 29, which indicates the slow speed relation of the motor, will be energized through the auxiliary contacts 12 of the field contactor 20. The motor will be accelerated from rest gradually in the manner heretofore explained, except that in this case the acceleration of the motor will be arrested at a speed determined by the full field relation of the motor.

Assume that the motor is thus accelerated .to the slow speed relation by momentarily depressing and releasing the push button 25 and it is desired to accelerate the motor to the half speed relation. By momentarily depressing the push button-24. the field contactor 20 will be de-energized through the upper contacts of the push button 24. This contactor will open and the signal lamp 29 will be extinguished by reason of the opening of the auxiliary contactsal associated with this contactor. lVhen the push button switch 24; comes into engagement with the lower contacts associated with this push button switch, the field contactor 19 will be closed through a circuit previously traced.

The maintaining circuit for the relay 22 will be undisturbed so that this relay will remain closed and the line contactor 13 will also remain closed. The contactors 15 and 16 will also remain closed so that all that will be changed will be the opening of the field contactor 20 and the closing of the field contactor 19 and the consequent lighting of the signal lamp 28. The motor will thus be accelerated from the slow speed relation to the half speed relation under the control of the fluttering relay 34 so that finally the motor will operate at a speed determined by the value of the resistance 17 which is now included in the shunt field circuit.

If instead of transferring from the slow speed to the half speed relation, the operator had desired to transfer to the full speed relation, he would depress momentarily the push button 23 so as to thereby deenergize the field resistor contactors 19 and 20 and thus insert the resistance sections 17 and 18 in the shunt field circuit of the motor, at the same time extinguishing the signal lamp 29 and lighting the signal lamp 27. The signal lamp 29 is extinguished by reason of the opening of the auxiliary switch 42 associated with the contactor 20. The relay 22 will remain energized as before and the line contactor 13 will also remain energized and closed ("as well as the cont-actors 15 and 16. The fluttering relay 34 will automatically open and close its contacts, dependin upon the motor armature current, thus e ecting a smooth and gradual acceleration from the slow speed relation to the full speed relation as determined by the value of the sections of resistances 17 and 18.

It will be apparent to those skilled in the art that the control system is such that the speed of the motor may be varied from any definite speed to any other definite speed either to increase or decrease the speed by simpl momentarily depressingl the pro er push utton' correspondin to t e particu ar speed desired, and it wi also be apparent that the signal lamp which corresponds to the speed desired will be lit and the si al lamp corresponding to the speed at w ich the motor was previously operating will be extinguished.

.The equipment may be shut down at any time by simply depressing the stop push button 26, thereby deenergizmg the various contactors and relays and causing these arts to assume their respective positions s own in the drawing. In case of an overload, the relay 30 will perform the same function as the stop button.

While the invention has a general application in systems of motor control in which it is desired to obtain any one of a plurality of definite speeds by simply momentarily depressing a manually operable switch corresponding to the speed desired, nevertheless the system has a particular a plication in systems wherein it is require that the arrangement shall be such that comparatively little intelligence is required on the part of the operator. Thus, by labelling the push buttons properly, the operator is required to merely operate a single push button for the particular speed which be desires and the arrangement is such that the desired speed relation is automatically effected without any further attention on the part of the operator. The invention has obvious features of simplicity of the apparatus employed and the simplicity of the general arrangement of the interconnection of the apparatus. Thereare no dash pots, ratchet switches, ilot motors, dial or drum switches and the like to get out of order and effect the successful operation of the s stem. It will also be observed that while t e invention is shown as one in which the definite speed relations are obtained by shunt field control, the invention is not necessarily limited to a shunt field control system, but is apprlicable generally to other forms of speed regulation as well, nor is the invention limited to the control of direct current motors. It will also be further observed that while the system is shown as one in which the control by the operator is effected at a single push button station having a plurality of spring return push buttons, nevertheless the system is also ap licable to arrangements in which it is deemed that the motor may be controlled from any one of a plurality of separate push button stations, each of which has a plurality of push buttons corresponding to the push buttons 23, 24., and 26, as indicated in the drawing. It is also to be further noted that while I have shown a system in which three definite speed relations of the motor are obtainable, the invention is not limited to this particular number of definite motor speeds, but is ap.

to represent the best embodiment thereof,

but I desire to have it understood that the apparatus. shown is onl illustrative and that the invention can e carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is 1. A system of motor control comprising electroresponsive switch mechanism for controlling the motor, a plurality of substantially similar separately operable manually operated switches, each of said switches corresponding to one of a plurality of different definite speeds of the motor and each of said switches being biased to a predetermined position, and means including electrical connections through which the said switch mechanism is controlled by a momentary operation of any selected one of the said manually operated switches to establish and then maintain the speed of the motor as determined by the manually operated switch which was selected.

2. A system of motor control comprising tromagnetic switches to establish and then maintain the speed of the motor corresponding to the manually operated switch which was momentarily operated. a i

3. A system of motor control comprising a plurality of contactors for controlling the motor, a plurality of spring return push button -switches,xeachrof which corresponds to one of a plurality of difierent definite speeds of the motor, and electrical connections through which control of said contactors is eifect-ed in response to a momentary operation and release of any selected push button switch to establish and maintain the definite speed of the motor corresponding to the se-- lected push button switch.

4. A system of motor control comprising a plurality of contactors for controlling the motor, a plurality of substantially similar separately operable manually switches for controlling the said contactors, one of said switches corresponding to a full running motor speed, another corresponding to a definite half speed of the motor and another corresponding toa definite slow speed of the motor, and electrical connections through which control of said contactors is effect-ed in response to a momentary operation of any selected one of said switches to establish and maintain the speed of the motor corresponding to the switch which was selected.

5. A system of motor control comprising a plurality of contactors for controlling the motor, a plurality of spring return push button switches, each of. which corresponds to a definite speed of the motor, and electrical connections through which control of said contactors and the motor is eifected whereby when the motor is operating at any one of the definite speeds corresponding to any one of the push button switches, the said contactors are selectively operated in re sponse to the momentary operation and release of any other one of the push button switches .to establish and maintain the speed of the motor corresponding to such other push button switch selected.

6. In a system 'of motor control, a plurality of substantially similar separately operable manually operated switches, each of which corresponds to one of a plurality of definite speeds of the motor and each of said switches being biased to a predetermined position, a plurality of signalling devices for indicating the selected motor speed, each of said devices corresponding to one of the said definite speeds of the motor, electroresponsive means for controlling the motor to establish the said definite speeds, and electrical connections through which the said means and the said signalling devices are controlled in response to a momentary operation of any one of said switches to establish the speed of the motor corresponding to the switch selected and energize the correspondin signalling device.

%.'A system of motor control com rising a plurality of contactors forncontrolliiig the motor,a p1ura1ity of spring return push button switches, each of which corresponds to one of a plurality of different definite speeds of the motor, a plurality of signalling devices for indicating the selected motor speed,

the said devices corresponding respectively operated 75 to the said definite speeds of the motor, and electrical connections through which control of said contactors and the said signalling devices is effected in response to a momentar operation and release of any selected pus button switch to establish and maintain the definite speed of the motor corresponding to the selected push button switch and energize the corresponding signalling device to indicate the selected speed.

8. In combination, an electric motor having a shunt field winding, a resistance in the motor field winding clrcuit, a plurality of contactors for controlling the said resistances and for controlling the connection of the motor to a source of supply, a plurality of spring return push button switches, eac of said switches corresponding to. a definite speed of the motor, and electrical connections through which a selective control of said contactors is efiected in response to a momentary operation of a selected push but-ton switch to connect the motor to a supply circuit, initially short-circuit the said resistance in the motor field winding circuit, automatically shunt the said resistance in the motor armature circuit as the speed of the motor increases, and automatically re-insert the value of resistance in the motor field winding circuit as determined by the push button switch selected to be operated.

9. In a system of motor control, an electric motor having a shunt field winding, a plurality of separately operable electromagnetic switches for controlling the motor, a plurality of spring return push button switches each of which corresponds to a diflerent definite speed of the motor, and electrical connections through which said push button switches effect a selective operation of said electromagnetic switches to connect the motor to a source of sup ly and govern the energization of said fiel d windmg to cause themotor to start and run at the speed corresponding to any selected push button switch in response to a momenta operation and release of the selected pus button switch, and after the motor is thus started the energization of said field winding is changed to change the speed of the motor to correspond to the speed of any of the other push button switches in response to a momentar operation and release of such other push utton switch.

In witness whereof, I have hereunto set my hand this 7th day of November, 1924.

JOHN A. HEPPERLEN. 

